Altering thermal conductivity in devices

ABSTRACT

Described are features to control distribution of thermal energy by structures such as portions of a case of a device. Various patterns of thermally conductive or insulating substances alter the thermal conductivity of a structure and provide selective directional distribution of thermal energy away from a hot spot caused by operation of a device component. The features result in a predetermined distribution of thermal energy across one or more structures, and may increase thermal uniformity.

BACKGROUND

With the increasing popularity of mobile devices, device manufacturershave sought ways to create devices with more processing power and othercapabilities in a smaller size. In many cases, increasing the processingpower of a device through the use of more powerful processors or addingother components may lead to an increase in heat generated by thosecomponents inside the device. Also the decreasing size of a device mayinhibit the device's ability to dissipate heat. Accordingly, smaller andmore powerful devices may be more prone to localized extremetemperatures. For example, a hot spot may develop which is uncomfortableto a user or which may result in damage to the component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example thermal distribution in a structure of adevice, exhibiting one or more hot spots and one or more thermaldistribution treatments to dissipate heat from the hot spots.

FIG. 2 depicts an example architecture for the device of FIG. 1 whichmay utilize one or more thermal distribution treatments.

FIG. 3 depicts an example thermal distribution in a structure of thedevice without the thermal distribution treatments described herein.

FIG. 4 depicts a cross sectional schematic of an enlarged portion of thedevice of FIG. 1 with at least one hot spot caused by operation of acomponent of the device and without the one or more thermal distributiontreatments.

FIG. 5 depicts a cross sectional schematic of the device of FIG. 1,including a treatment on an interior surface.

FIG. 6 depicts a plan view schematic of a structure for the device,including a radially symmetric treatment on a surface of the structure.

FIG. 7 depicts a plan view schematic of a structure for the device,including an asymmetric treatment on a surface of the structure.

FIG. 8 depicts a graph of thermal conductivity for a treatment, varyingas a function of distance outward from a hot spot.

FIG. 9 depicts a cross sectional schematic of a structure for the deviceincluding a treatment to conduct heat transversely along a surface ofthe structure.

FIG. 10 depicts a cross sectional schematic of a structure for thedevice which includes a treatment of varying thickness on an interiorsurface of the structure to conduct heat transversely.

FIG. 11 depicts a cross sectional schematic of a structure for thedevice, including a multi-layered treatment to conduct heat transverselyin the structure.

FIG. 12 depicts a cross sectional schematic of a structure for thedevice, including a treatment on an exterior surface of the structure toconduct heat transversely in the structure.

FIG. 13 depicts a cross sectional schematic of a structure for thedevice, including a treatment of varying thickness on an exteriorsurface of the structure to conduct heat transversely in the structure.

FIG. 14 depicts a cross sectional schematic of a structure for thedevice, including an intermediate layer to conduct heat transversely.

FIG. 15 depicts a cross sectional schematic of a structure for thedevice, including an intermediate layer of varying thickness to conductheat transversely, the intermediate layer having a thickness thatdecreases with distance outward from a heat generating component.

FIG. 16 depicts a cross sectional schematic of a structure for thedevice, including an intermediate layer of varying thickness to conductheat transversely, the intermediate layer having a thickness thatincreases with distance outward from a heat generating component.

FIG. 17 depicts a flow diagram of a method of manufacture for applying atreatment to a wall, to alter the thermal conductivity of at least aportion of the wall.

FIG. 18 depicts a flow diagram of a method of manufacture for a sheetthat may be applied to a wall of a device, to alter the thermalconductivity of at least a portion of the wall.

Certain implementations and embodiments will now be described more fullybelow with reference to the accompanying figures, in which variousaspects are shown. However, various aspects may be implemented in manydifferent forms and should not be construed as limited to theimplementations set forth herein. Like numbers refer to like elementsthroughout.

DETAILED DESCRIPTION

This disclosure describes implementations of features to vary thethermal conductivity of one or more structures of a device to providefor a more uniform distribution of heat across the one or morestructures. Implementations include surface features for interior orexterior surfaces of one or more walls of a device. Implementations alsoinclude features for an intermediate layer of a wall that is situatedbetween an exterior and an interior surface of the wall. The featuresdescribed herein may vary the thermal conductivity transversely along aplane that is parallel to a primary plane described by the overalllength and width of the wall. These features facilitate the conductionof heat away from hot spots caused by operation of heat generatingcomponents. By conducting heat transversely away from hot spots, hotspots in the device wall may be reduced in intensity or number, thusreducing the likelihood of an adverse user experience that may resultfrom such hot spots.

FIG. 1 depicts an example thermal distribution 100 as a plan view of astructure 102 of a device. The structure 102 is depicted from outsidethe device which presents a broad side of the device, such as the backplate or case of the device. As used herein, the structure 102 mayinclude a portion of the device such as one or more interior surfaces(e.g., at least partly enclosed by the case), one or more exteriorsurfaces, or both interior and exterior surfaces. The structure 102 maybe substantially flat, or may be at least partly curvilinear.

The thermal distribution 100 includes isothermic curves, where eachcurve connects points of equal temperature and where each curverepresents a different temperature. In the example shown, the structure102 exhibits one or more temperature maxima such as hot spots 104(1) and104(2). Also shown are one or more temperature minima such as cool spots106(1) and 106(2). As used herein, the term hot spot 104 refers topoints, areas, or portions of a surface that have a higher temperaturethan a predetermined threshold value. In some implementations, thepredetermined threshold value is an average temperature of the surfaceor a certain percentage of the average temperature (e.g., 110% of theaverage temperature). Such hot spots may feel hot to the touch of a userof the device, or appear hot when the device is thermally imaged usingan infrared imaging system. The hot spots 104 may be areas of maximumtemperature across the surface, or may be local maxima relative to anearby portion of the surface. As used herein, cool spots 106 refer topoints, areas, or portions of a surface that have a temperature lowerthan a predetermined threshold value, such as the average temperature ofthe surface. Although the structure 102 is shown having two hot spotsand two cool spots, implementations support a structure exhibiting anynumber of hot spots 104 or cool spots 106.

The hot spots 104 may be caused by operation of heat generating devicecomponents. Devices may include one or more electrical components suchas processors, central processing units (CPUs), graphics processingunits (GPUs), memory, light emitting diodes, power handling circuitry,and so forth that generate heat during their operation. In some cases,the surface of a device may have hot spots 104 in one or more portionsof the surface in proximity to, or otherwise correlated with, thelocation(s) of heat-generating electrical component(s) 108 within thedevice. In the example shown in FIG. 1, the hot spot 104(1) iscorrelated with a location of a heat generating component 108(1), andthe hot spot 104(2) is correlated with a location of a heat generatingcomponent 108(2).

For commercially available devices that have outer walls made of aplastic, external hot spot temperatures may reach 50° Celsius (C.) andmay exceed a comfortable temperature for a user. For devices that haveouter walls made of aluminum or some other metal, external hot spottemperatures may reach 40-45° C. This hot spot temperature may alsoexceed a comfortable temperature for a user, given that a metal wall hasa higher thermal conductivity than plastic, and may conduct heat moreefficiently into a user's skin when the user is holding the device.Accordingly, the hot spot temperatures of a plastic-walled ormetal-walled device may create discomfort for a user using the device,and in certain extreme cases may even lead to burns when the device isused for a prolonged period of time. Implementations described hereinvary the thermal conductivity of one or more structures of a device,such as surfaces or layers of a wall of a device, through the use offeatures such as the one or more thermal distribution treatments 110.

Implementations may employ any number of features to facilitate heatconduction. In some implementations, a feature may include a treatmentof the structure 102. As used herein, a treatment may include one ormore materials arranged on a surface of the structure 102 as a layer orcoating of any thickness. A treatment may also include one or morematerials incorporated into the material of the structure 102, such as atreatment that is interposed as an intermediate layer between otherportions of the structure 102. The treatments described herein may beadded to the structure 102 during or after manufacture of the structure102, or may be part of an initial composition of the structure 102.Implementations support a treatment 110 that is at least partly radiallysymmetric, such as one or more of a star-shaped pattern, an ellipticalpattern such as a circular pattern, and so forth. Implementations alsosupport a treatment 110 that is at least partly symmetric about one ormore axes, such as one or more of a polygonal pattern such as arectangular pattern, a stripe pattern, and so forth. Implementationsalso support a treatment 110 that is substantially asymmetric.

FIG. 1 shows a thermal distribution treatment (“treatments”) 110(1) todistribute heat from the hot spot 104(1), and a thermal distributiontreatment 110(2) to distribute heat from the hot spot 104(2). Thethermal distribution treatments 110(1) and 110(2) provide a variation inthe thermal conductivity of the structure 102, and enable the structure102 to conduct heat in a predetermined transverse direction. The thermaldistribution treatments 110 may comprise materials arranged in aparticular pattern and configured to direct the flow of heat. As shownin FIG. 1, the thermal distribution treatments 110(1) and 110(2) enableconduction of the transversely diffusing heat 112 transversely (e.g., inan x-y plane of the structure 102) away from the hot spots 104(1) and104(2) toward the cool spots 106(1) and 106(2). In this way, the thermaldistribution treatments 110(1) and 110(2) enable a particulardistribution of heat in the x-y plane, and thus a predetermineddistribution of heat that is conducted outward (e.g., along a z-axis) bythe structure 102 and away from the device.

By using the thermal distribution treatments 110 a particular heatdistribution across an outer surface or other structure of the device isprovided. This may include reduction in the temperature of one or morehot spots on the outer surface or other structure of the device, thusproviding a more comfortable user experience.

The thermal distribution treatments 110 may comprise a substance that isa thermal conductor or a thermal insulator. In some implementations, thetreatment 110 may employ multiple substances of various thermalconductivities, or a composite of more than one substance.Implementations support any thermally conducting substance, includingbut not limited to: metals, such as aluminum, nickel, copper, and soforth; thermally conductive inks; or various carbon allotropes such asgraphene. Implementations support any thermally insulating substance,including but not limited to: metal oxides, such as aluminum oxide;plastics; aerogels; ceramics; silicates, or various polymers such aspolytetrafluoroethylene.

In some implementations, the treatment 110 may include one or morelayers on an interior surface of a structure of the device. Thetreatment 110 may include a pattern of a thermally conductive substanceon the interior surface of the structure 102. The structure 102 may havea lower thermal conductivity than material in the treatment 110 suchthat the structure 102 may be considered a thermal insulator. Forexample, a pattern of a thermally conductive metallic substance may beimposed on the interior surface of a plastic wall of the device case,the plastic being a thermal insulator. In some implementations, athermally conductive pattern may be imposed on a thermally insulatinglayer or substrate that is in contact with the interior surface of thestructure.

In some implementations, the treatment 110 may include one or morelayers on an exterior surface of the structure 102 of the device. Thetreatment 110 may include a pattern of a thermally insulating substanceon the exterior surface of the structure 102, where the structure 102has a higher thermal conductivity than the material of the pattern suchthat the structure 102 may be considered a thermal conductor. Forexample, a pattern of a thermally insulating substance may be imposed onthe exterior surface of a metallic, thermally conductive wall of thedevice. In some implementations, a thermally insulating pattern may beimposed on an intermediate layer or substrate that is in contact withthe exterior surface of the structure.

In some implementations, the structure 102 of the device may include anexterior layer and an interior layer, and the treatment may include oneor more intermediate layers that are situated at a z-level between theexterior layer and the interior layer of the structure. For example, thestructure 102 may include exterior and interior layers of a thermalinsulator with an intermediate layer of a thermal conductor in between.In some cases, a thermally conductive via or thermal conduit maythermally couple the conducting intermediate layer with a heatgenerating component 108 of the device, such as a processor.

The treatment 110 may be varied to produce particular heat distributionpatterns. Thickness of the treatment 110 may be varied to achieve avarying thermal conductivity across the surface or treatment layer.Composition of the surface treatment 110 or layer may be varied toachieve a varying thermal conductivity across the surface or layer.Thermal conductivity of the material used in the treatment 110 may bevaried to control the heat conduction transversely within the surface orlayer. The variance of the thermal conductivity in the transversedirection may serve to conduct the heat away from one or more hot spotsto one or more cooler spots of the structure of the device whileproviding for a more consistent outer temperature of the device.

The treatments 110 may use patterns of thermally conductive orinsulating substances. The patterns may exhibit at least partialsymmetry, such as radial symmetry or symmetry about an axis in the x-yplane parallel to the surface of the structure. In some cases, patternsmay be asymmetric. The material of the treatment 110 may includedifferent patterns of different substances, either at the same z-levelrelative to a surface of the structure, or at different z-levels. Forexample, a first material may be emplaced in a regular repeating gridwhile a second material may be emplaced over at least a portion of thefirst material with regard to maintaining a particular pattern.

Some implementations may employ a substance in the treatment 110 that isdirectionally anisotropic with regards to at least thermal conductivity.For example, graphene may be employed which exhibits a higher thermalconductivity in a transverse, x-y plane than it does along a z-axis.Such anisotropic substances may be employed to create heat corridors tomove heat transversely along a surface from a hot spot to a cool spot,while at least partly inhibiting the conduction of the heat along az-axis through the structure. Other implementations may employsubstances that are more isotropic in thermal conductivity, exhibitvariable isotropy, and so forth.

As used herein, thermal conductivity refers to a rate of diffusion ofheat through a material. Different materials may have different thermalconductivities. As used here, a material or substance referred to as athermal conductor may have a thermal conductivity that is higher than athreshold conductivity. For example, a substance may be considered athermal conductor if its thermal conductivity is higher than 2Watts/meter×Kelvin at room temperature. A material or substance referredto as a thermal insulator may have a thermal conductivity that is lowerthan a threshold conductivity. For example, a substance may beconsidered a thermal insulator if its thermal conductivity is lower than2 Watts/meter×Kelvin at room temperature.

FIG. 2 depicts a schematic 200 of an example device 202 which may employfeatures such as the various thermal distribution treatments 110described herein. Implementations may be employed using any type ofdevice 202, including but not limited to a mainframe computer, a servercomputer, a desktop computer, a personal computer, a laptop computer, atablet computer, an electronic book reader, a wearable computer, animplanted computer, a mobile phone, a thin client, a terminal, a gameconsole, a mobile gaming device, and the like. Implementations may alsobe used in other types of industrial, commercial, and consumerelectronics devices, such as televisions, video monitors, audio systemcomponents, network infrastructure devices, printers, scanners,industrial controls, commercial appliances, and so forth. Moreover,although the examples discussed herein refer to devices with heatgenerating electronic components, implementations may also be employedto alter the thermal properties of devices that may include one or moreheat generating mechanical components.

As shown in FIG. 2, device 202 has a case 204 which at least partlyencloses one or more components of device 202. The case 204 may becomposed of a thermally conductive substance such as a metal, athermally insulating substance such as plastic or ceramic, or anycombination of various substances. In the example shown, device 202includes a display 206, such as a light-emitting diode (LED) display, aliquid crystal display (LCD), an electrophoretic display, or anothertype of display.

The device 202 may include various components, including electroniccomponents or mechanical components. At least some of these componentsmay generate heat during their operation. In the example shown, thedevice 202 includes one or more processors 208. The processor(s) 208 maybe configured to execute one or more stored computational instructions,and may comprise one or more cores. The processor(s) 208 may be on oneor more dies or incorporated into a motherboard of the device 202.

The device 202 may also include one or more graphics processing units(GPUs) 210 which operate to receive image information and build imagesand video streams to be displayed on the display 206. The GPU(s) 210 maybe included on a video card, or on a motherboard of the device 202. Insome cases, at least some functionality of the GPU(s) 210 may beincorporated into the processor die that includes the processor(s) 208.

The device 202 may include a memory 212, which may be one or more of anelectronic storage medium, a magnetic storage medium, an optical storagemedium, a quantum storage medium, a mechanical storage medium, and soforth. The memory 212 may provide storage of computer readableinstructions, data structures, program modules, and other data for theoperation of the device 202. The device 202 may include one or morenetwork interface(s) 214 such as transmitter(s) or transceiver(s), toenable the device 202 to communicate with other devices over a wired orwireless network. The device 202 may also include a power supply 216,such as a battery. The device 202 may include one or more othercomponents 218, such as input/output (I/O) interface(s), I/O device(s),and the like.

FIG. 3 depicts an example thermal distribution 300 of the structure 102without the thermal distribution treatment 110 applied to the structure102. Accordingly, the thermal distribution 300 exhibits a less uniformdistribution of heat across the structure 102, with the hot spots 104(1)and 104(2) being more localized and exhibiting greater localtemperatures than in the example distribution 100.

FIG. 4 depicts a schematic 400 of a cross sectional view of thestructure 102 without the treatment 110. As shown, the structure 102exhibits a hot spot 104 caused by the heat generated from the operationof the heat generating component 108. In this example, outward diffusingheat 402 is conducted through the structure 102 from an interior surfaceto an exterior surface. In FIG. 4 and in other figures, heat isrepresented as a vector quantity with the arrow indicating a directionin which the heat is conducted. In the example shown in schematic 400,the outward diffusing heat 402 may be a vector quantity with anorthogonal component that is substantially orthogonal to a surface ofthe structure 102, and with a transverse component that is substantiallyparallel to a surface of the structure 102. Without the treatment 110described herein, the outward diffusing heat 402 is conducted outwardthrough the structure 102 non-uniformly, causing the externallymanifested hot spot 104.

FIG. 5 depicts a cross sectional schematic 500 of the device 202 alongline “A”, including a feature to facilitate heat distribution. In thiscase, the feature comprises a treatment 110 on an interior surface ofthe structure 102. In the implementation shown, the structure 102 is aback wall of the device 202, on a side of the device 202 opposite thedisplay 206. In other implementations, treatments 110 may be used withany of the structures 102 of the device 202, and are not limited totreatments 110 on the back wall.

In the implementation shown, the structure 102 includes the treatment110 and a substrate 502. For example, the substrate 502 may comprisepolytetrafluoroethylene (PTFE) and the treatment 110 may be printed uponthe substrate 502 prior to assembly. The treatment 110 illustrated hereis on an interior surface of the structure 102, and the substrate 502 isbetween the treatment 110 and an exterior surface of the device 202.

In some embodiments, the treatment 110 is composed of a substance thathas a higher thermal conductivity than the substrate 502, such that thetreatment 110 is a thermal conductor relative to the substrate 502, andthe substrate 502 is a thermal insulator relative to the treatment 110.In some implementations, a thermal conduit 504 may be thermally coupledboth to the heat generating component 108 and the treatment 110 to allowheat generated by the heat generating component 108 to transfer viaconduction to the treatment 110.

In some implementations, the device 202 may include one or more exteriorfeatures designed to improve distribution of heat to the environmentwithin which the device 202 resides. For example, the device 202 mayinclude on its outer surface an external feature 506, such as a heatsink, plate, fin, protuberance, or other external thermal radiationstructure. In such cases, the treatment 110 may be arranged as a heatcorridor to conduct heat from a hot spot toward the location of theexternal feature 506, to enable the heat to more efficiently be radiatedaway from the device 202.

FIG. 6 depicts a schematic 600 of a plan view of the structure 102 shownin schematic 500, including the treatment 110 on a surface of thestructure 102. In the implementation shown, the treatment 110 is imposedon the substrate 502, on an interior surface of the structure 102. Inthis example, the treatment 110 is at least partly radially symmetric,with portions radiating outward from a point corresponding to the hotspot 104.

In this example, the treatment 110 is a thermally conducting substance.In other implementations, the treatment 110 may be a thermal insulator.The treatment 110 may be arranged to control the transversely diffusingheat 112 transversely along a surface of the structure 102 away from thehot spot 104 to another portion of the structure.

In some implementations, the device 202 includes one or more externalthermal dissipation structures such as the external feature 506. In suchcases, the treatment 110 may be arranged to enable the transverselydiffusing heat 112 to be efficiently conducted in a transverse directionto a location on the substrate 502 that is proximal in the x-ytransverse plane to the external feature 506. For example, the treatment110 may carry heat to a spot underneath the external feature 506.

The example implementation of FIG. 6 includes a magnified view of thetreatment 110(2) and a further enlargement illustrating a treatmentpattern 602. In some implementations, the treatment pattern 602 for athermally conducting or thermally insulating treatment 110 may becomposed of an arrangement of shapes of the substance or material thatforms the treatment 110. Such shapes may be circular, elliptical,polygonal, or irregularly shaped. The shapes may have any degree or typeof symmetry, or may be asymmetric. The shapes may be at least partlycontiguous, or may be separated. For example, in cases where thetreatment 110 is a thermally conducting material, the shapes may be atleast partly contiguous to facilitate heat conduction. In cases wherethe treatment 110 is a thermally insulating material, the shapes in thetreatment pattern 602 may be separated to inhibit heat transfer. Theshapes may be arranged with any thickness, or in multiple layers of thesame or differing substances to facilitate thermal conduction orinsulation. In the example shown, the treatment pattern 602 is a regularrepeating pattern. However, implementations may employ patterns that arerandom, pseudo-random, or irregular to any degree, such as irregulartreatment pattern 604.

FIG. 7 depicts an implementation having a feature for heat distribution,the feature including a treatment 110 that is not symmetric. Thetreatment 110(1) is arranged in an asymmetric arrangement to conduct thetransversely diffusing heat 112 transversely away from the hot spot104(1). The treatments 110 may exhibit any type of symmetry relative tothe structure 102 being treated, including radial symmetric about one ormore center points, lateral symmetry about one or more axes, partialsymmetry of any type, or any combination of symmetries. The treatments110 may also exhibit no symmetry relative to the structure 102 beingtreated.

In implementations where the treatment 110 is a thermally conductingmaterial imposed on the substrate 502 which is a thermally insulatingmaterial, the treatment 110 may be arranged such that its thermalconductivity varies over the structure being treated. In someimplementations, the thermal conductivity of the treatment 110 maydecrease with increasing distance from a point in the hot spot 104,along one or more vectors radiating outward from one or more points inthe hot spot 104.

In implementations where the treatment 110 is a thermally insulatingmaterial imposed on the substrate 502 which is a thermally conductingmaterial, the treatment 110 may be arranged such that its thermalresistivity varies over the structure being treated. In someimplementations, the thermal resistivity of the treatment 110 maydecrease with increasing distance from a point in the hot spot 104,along one or more vectors radiating outward from one or more points inthe hot spot 104.

FIG. 8 illustrates as a graph 800 a variance in thermal conductivity forthe treatment 110, varying as a function of distance outward from thehot spot 104. In graph 800, the vertical axis is a thermal conductivityfrom a minimum thermal conductivity 802 to a maximum thermalconductivity 804. In some cases, the minimum thermal conductivity 802 isthe thermal conductivity of the substrate 502, e.g., the thermalconductivity at a point on the surface where there is no treatment 110.The horizontal axis is a distance from a point in the hot spot 104 froma minimum distance 806 to a maximum distance 808 (e.g., the extent ofthe treatment 110 along the surface). In cases where the treatment 110is a material that is anisotropic in thermal conductivity, such that itsthermal conductivity in a transverse direction (e.g., in plane) differsfrom its thermal conductivity in a direction orthogonal to thetransverse (e.g., out of plane), the vertical axis may measure thermalconductivity in a transverse direction.

As shown in graph 800, the transverse thermal conductivity as a functionof distance 810 may decrease as the distance from a point in the hotspot 104 increases, such that transverse thermal conductivity decreaseswith distance from the hot spot 104. In this way, implementations mayallow for a more efficient transverse movement of heat outward from thehot spot 104 at locations near the hot spot 104, and less efficientmovement of heat outward as the distance from the hot spot 104increases. In some implementations, the transverse variation of thethermal conductivity may be through a variation in a thickness of thetreatment 110. For example, for some materials a thicker layer ofconducting material may provide for a higher thermal conductivity. Insome implementations, the variation in thermal conductivity may beaccomplished through a variation in the pattern in which the material oftreatment 110 is placed, such as patterns 602 and 604, or through avariation of the density of the material. In some implementations, thetransverse thermal conductivity may increase with distance from the hotspot 104. Further, in some implementations the transverse thermalconductivity may exhibit one or more inflection points where it changesfrom increasing to decreasing, or from decreasing to increasing.

Implementations support the use of any type of thermal conductor in thetreatment 110, including metals such as copper, aluminum, nickel, orother metals. Implementations may also support the use of thermallyconductive inks. The above-listed substances are generally isotropic andnon-directional in thermal conductivity. Implementations also supportthe use of anisotropic substances, which may have a thermal conductivitythat varies based on direction. For example, graphene is a substancecomposed of carbon atoms arranged in sheets, where each sheet is ahexagonal arrangement of carbon atoms. The thermal conductivity ofgraphene in a transverse direction in plane with the sheets isapproximately 100 times greater than its thermal conductivity out ofplane, in an orthogonal direction from one sheet to another sheet.Implementations may employ graphene in at least a portion of thetreatment 110 to provide for more efficient heat transport transverselyaway from the hot spot 104.

In some implementations, the transverse variation of the thermalconductivity may be accomplished through the use of multiple conductingmaterials having different thermal conductivities in the treatment 110.For example, the treatment 110 may include a higher thermally conductivesubstance closer to the hot spot 104, and a lower thermal conductivesubstance farther from the hot spot 104. As another example, thetreatment 110 may be a combination of two or more substances withdifferent thermal conductivities. The treatment 110 may employ acombination with a higher proportion of a more conductive substancecloser to the hot spot 104, and a combination with a lower proportion ofthe more conductive substance farther from the hot spot 104. In thisway, the transverse thermal conductivity of the structure may be alteredto provide for efficient conduction of heat away from the hot spot 104.

FIG. 9 depicts a cross sectional schematic 900 of one implementation ofthe structure 102. As shown, the treatment 110 enables the transverselydiffusing heat 112 to be conducted transversely away from the heatgenerating component 108. Because the transversely diffusing heat 112 isspread transversely in the treatment 110, the outward diffusing heat 402conducted outward through the substrate 502 is more evenly distributedtransversely across the structure 102. Consequently, the temperature ofan outer surface of the structure 102 may be more uniform, or exhibitingfewer or less extreme hot spots 104, than would otherwise be the case inthe absence of the treatment 110. The schematic 900 illustratesimplementations in which the treatment 110 is substantially uniform inthickness. In such cases, the thermal conductivity may be varied throughuse of different conducting substances or a varying mixture of thermallyconducting and insulating substances in the treatment 110, to providefor more efficient diffusion of the transversely diffusing heat 112closer to a hot spot.

Although FIG. 9 and other figures depict the heat generating component108 as separated from the treatment 110, in some cases the heatgenerating component 108 may be adjacent to the treatment 110 orthermally coupled to the treatment 110. For example, a thermal conduitmay conduct heat from the heat generating component 108 to the treatment110.

FIG. 10 depicts a cross sectional schematic 1000 of anotherimplementation of the structure 102. The schematic 1000 illustrates animplementation in which the thickness of the treatment 110 varies acrossa surface of the structure 102. For example, the thickness of thetreatment 110 may be inversely proportional to a distance from a hotspot 104, to provide for a thermal conductivity that decreases withdistance from the hot spot 104. Because the transversely diffusing heat112 is spread transversely in the treatment 110, with greater efficiencycloser to the hot spot, the outward diffusing heat 402 conducted outwardthrough the substrate 502 may be more evenly distributed across thestructure 102.

FIG. 11 depicts a cross sectional schematic 1100 of anotherimplementation of the structure 102, in which the features for heatdistribution include a multi-layered arrangement to conduct heat fromthe heat generating component 108 transversely along the structure 102.In this implementation, an intermediate layer 1102 is arranged betweenthe treatment 110 and the substrate 502. In some implementations, thetreatment 110 may be a thermally conducting substance, and theintermediate layer 1102 may be a thermally insulating substance, or asubstance that has a lower thermal conductivity than the treatment 110.Implementations support any type of thermal insulator, including analuminum oxide or other metal oxides, plastics, aerogels, ceramics,various silicates, or other thermally insulating materials. For example,the intermediate layer 1102 may comprise polytetrafluoroethylene.

The use of an insulating intermediate layer 1102 may provide for moreefficient transverse conduction of the transversely diffusing heat 112away from the hot spot 104. In some implementations, the thickness ofone or more of the treatment 110 and the intermediate layer 1102 mayvary with location on a surface of the structure 102. For example,thickness of the insulating, intermediate layer 1102 may decrease withdistance from the hot spot 104, to allow more outward diffusing heat 402heat to diffuse outward along the z-axis direction to an externalsurface of the structure 102 as the transverse distance increases fromthe hot spot 104.

Some implementations may include at least one thermal conduit 1104,which thermally couples the treatment 110 to the substrate 502. Use ofthe thermal conduit 1104 may increase the efficiency of heat diffusingfrom the treatment 110 to the substrate 502.

Although FIG. 11 depicts the intermediate layer 1102 and the treatment110 having a similar extent along the surface of the substrate 502,embodiments are not so limited. In some cases the intermediate layer1102 span a different surface area, have a different shape than thetreatment 110, or the treatment 110 may partially overlap theintermediate layer 1102.

FIG. 12 depicts a schematic 1200 of a cross sectional view of thestructure 102, including a heat distribution feature that comprises thetreatment 110 on an exterior surface of the structure 102 to conductheat transversely in the structure 102. In the implementation shown, thestructure 102 includes the substrate 502 that may be a thermallyconducting substance such as aluminum, another metal, or combination ofmetals. The treatment 110 on an exterior surface of the structure 102comprises a thermally insulating substance. Operation of the heatgenerating component 108 may cause a hot spot, such that the outwarddiffusing heat 402 diffuses in a z-axis direction through the structure102 toward an exterior surface. In this example, the outward diffusingheat 402 is uneven, with more heat diffusing outward at locations in thex-y plane closer to the hot spot caused by the heat generating component108. As the outward diffusing heat 402 nears the thermally insulatingtreatment 110, it diffuses more transversely away from the center of thehot spot, as the transversely diffusing heat 112. In this way,implementations may provide for a more even temperature across theexterior of the structure 102. As illustrated here, the thickness of thetreatment 110 may be substantially consistent. In such cases, thethermal resistivity (e.g., the reciprocal of thermal conductivity) ofthe treatment 110 may be varied through use of a varying mixture ofdifferent substances having different thermal resistivities.

FIG. 13 depicts a cross sectional schematic 1300 of one implementationof the structure 102. This implementation shows the treatment 110 ofvarying thickness on an exterior surface of the substrate 502 of thestructure 102 to conduct the transversely diffusing heat 112 in thestructure 102. In this example, the treatment 110 is a thermallyinsulating material. As the outward diffusing heat 402 nears theinsulating treatment 110, the treatment 110 provides for the transversediffusion of heat 112 away from the hot spot 104 caused by the heatgenerating component 108, with greater transverse diffusion closer tothe hot spot 104 given the varying thickness of the insulating treatment110.

FIG. 14 depicts a cross sectional schematic 1400 of anotherimplementation of the structure 102. In this example, the structure 102includes features for heat distribution, including an internal layer1402, an external layer 1406, and an intermediate layer 1404 between theinternal layer 1402 and the external layer 1406. One or more of theselayers may comprise treatments 110 deposited onto layers which are thenassembled, or fabricated within the material of the structure 102.

In some implementations, the internal layer 1402 and the external layer1406 are each composed of a thermally insulating substance orsubstances, and the intermediate layer 1404 is composed of a thermallyconducting substance, or a substance that is more thermally conductingthan layers 1402 and 1406. In the implementation shown, the outwarddiffusing heat 402 diffuses along a z-axis direction from an interiorsurface of the structure 102 through the interior layer 1402, to theintermediate layer 1404. On reaching the intermediate layer 1404, theoutward diffusing heat 402 may then diffuse in a transverse directionaway from the hot spot, as the transversely diffusing heat 112. In thisway, the intermediate layer 1404 may provide for a more transverselyuniform distribution of the transversely diffusing heat 112, so that theoutward diffusing heat 402 may diffuse up through the external layer1406 more uniformly. This may lead to a more uniform externaltemperature of the structure 102 or a pre-determined heat dissipationpattern.

Some implementations may further include a thermal conduit 504 thatthermally couples the heat-generating component 108 with the thermallyconductive intermediate layer 1404. The thermal conduit 504 may passthrough the internal layer 1402, and may be composed of a thermallyconductive material to enable more efficient diffusion of the outwarddiffusing heat 402 through the internal layer 1402 to the intermediatelayer 1404.

In some cases, the intermediate layer 1404 may be arranged such that itsthermal conductivity is higher toward the center of a hot spot, andlower with increasing distance from the hot spot. This may provide for apredetermined conduction of the transversely diffusing heat 112 in theintermediate layer 1404.

FIG. 15 depicts a schematic 1500 of a cross sectional view of thestructure 102, for some implementations. As above, the heat generatingcomponent 108 may couple to the intermediate layer 1404 with a thermalconduit 504. In this implementation, the intermediate layer 1404 issituated between the internal layer 1402 and the external layer 1406,and the thickness of the intermediate layer 1404 varies with distancefrom the hot spot 104 caused by the heat generating component 108. Thismay provide for a thermal conductivity of the intermediate layer 1404that decreases with the transverse distance outward from the hot spot104. This may enable more efficient transverse diffusion of thetransversely diffusing heat 112 away from the hot spot, and may lead toa more uniform outward diffusion of the outward diffusing heat 402 asdescribed above. In some implementations, the extents of the internallayer 1402, the intermediate layer 1404, and the external layer 1406 maydiffer, such that one or more of these layers cover different surfaceareas in the structure 102. Furthermore, as described above, the layersmay comprise treatments 110 which are deposited onto an adjacent layer,or formed within the layer itself.

FIG. 16 depicts a cross sectional schematic 1600 of anotherimplementation of the structure 102. As above with regard to FIG. 15,the intermediate layer 1404 may be arranged between the internal layer1402 and the external layer 1406. As above, the thermal conduit 504 maycouple the heat generating component 108 and the intermediate layer1404. However, in this figure the thickness of the intermediate layer1404 increases with distance from the hot spot 104 caused by the heatgenerating component 108, to provide for a thermal conductivity of theintermediate layer 1404 that increases with the transverse distanceoutward from the hot spot. In some implementations, this may enabletransverse diffusion of the transversely diffusing heat 112 in apredetermined pattern away from the hot spot 104. This, in turn, mayresult in a more uniform outward diffusion of the outward diffusing heat402 as described above.

In some implementations, the intermediate layer 1404 may not have aclearly defined transition to the internal layer 1402 or the externallayer 1406, and may be composed of a material that is incorporated intothe structure 102 as a dopant. For example, the intermediate layer 1404may be a thermal conductor such as a carbon fiber material that isincorporated into the material of the structure 102 through a dopingprocess to increase a thermal conductivity of a portion of the structure102.

The various implementations described above may be combined in any wayfor additional implementations. For example, one or more implementationsmay include any combination of interior and exterior surface treatments,each with one or more patterns of thermally conducting or insulatingmaterial. Moreover, one or more implementations may include anycombination of interior and exterior surface treatments with anintermediate layer for more efficient transverse diffusion of heatbefore it reaches the outer surface of a device. Various implementationsmay also incorporate heat corridors to transfer heat toward an externalthermal radiation structure (e.g., a heat sink).

Illustrative Processes for Applying Treatments

FIG. 17 depicts a flow diagram 1700 of a process for applying atreatment to a structure 102, to alter the thermal conductivity of atleast a portion of the structure 102. In some implementations, theprocess may be at least a portion of a method for manufacturing a devicesuch as the device 202 or components suitable for use in the device 202.

At 1702, an external heat distribution of the device is analyzed. Insome embodiments, this analysis may be based on an analytic modeldeveloped mathematically or computationally given known heat-generatingcharacteristics of one or more components of the device, the materialscomposing the various components and casing of the device, the physicalarrangement of the components and the casing, or other factors. In someembodiments, the analysis may be at least partly experimental andperformed through real-time monitoring and thermal imaging of a devicewhile it is operating. Some embodiments may include multiple stages inan analysis, with one or more early stages being based on a mathematicalor computational model, and later stages including refinements of thatmodel based on experimental observation of the device.

In some cases, the analysis of the device may be based on a normaloperation mode for the device, based on previously observed anddocumented common use of the device by users. In some cases, theanalysis of the device may be based on more unusual use conditions thatmay provide corner case example scenarios for operation of the device.For example, the analysis of the device may be performed where thedevice is being used to playback a long video file, such that the devicemay be running hotter than under non-playback conditions. In someembodiments, the analysis of the device may be based on the devicerunning in a steady state, following a period of transient activity whenthe device itself or processes on the device are starting up.

At 1704, based on the analysis, one or more hot spots 104 may beidentified for the device. In some implementations cool spots may alsobe identified. At 1706, one or more surface treatment(s) may bedetermined that provide for a predetermined heat distribution across oneor more outer surfaces of the device. In some embodiments, where theanalysis at 1702 is based on an analytic model, the determination ofsurface treatment(s) may be through a computational process to determinea surface treatment which minimizes or eliminates hot spots 104, reducesthe intensity of hot spots 104, or generally provides for the greateruniformity in the outer temperature of the device. Such a calculationmay be through a multivariate computational analysis that simultaneouslyminimizes one or more determined temperature maxima of hot spots 104, orminimizes a variance of the temperature across the outer surface of thedevice.

At 1708, the one or more determined surface treatments are applied toone or more surfaces of the device. Various methods may be employed tocreate patterns or layers of thermally conducting or thermallyinsulating substances on surfaces. To create patterns or layers of aninsulating aluminum oxide or other metal oxide, an anodization processmay be employed. To create patterns of layers of a conducting ink, aninkjet or other printing or lithographic process may be employed. Otherpossible methods of affixing or otherwise controlling the pattern of thesubstances include, but are not limited to, sputtering, painting,lamination, direct deposit onto another substance, labeling, plating,etching, and so forth.

FIG. 18 depicts a flow diagram 1800 of a process for applying atreatment to a substrate that may be applied to a structure of a device,to alter the thermal conductivity of at least a portion of the structure102. In some implementations, the process may be at least a portion of amethod for manufacturing a sheet to be used to alter the thermalproperties of a device such as the device 202. In some implementations,the sheet may be designed and manufactured as an after-market product tobe applied to a device previously purchased by an end-user. For example,the sheet may be at least a portion of a cover designed to fit thedevice and alter its thermal properties. As another example, the sheetmay be a laminate, sticker, or label designed to be affixed to a surfaceof the device to alter its thermal properties.

At 1802, an analysis is performed of the external heat distribution of atest device. At 1804, based on the analysis, one or more hot spots 104are identified for the test device. In some implementations cool spots106 may also be determined. At 1806, one or more surface treatments maybe determined to provide a predetermined heat distribution. Steps 1802,1804, and 1806 may proceed in a substantially similar manner to steps1702, 1704, and 1706 described above.

At 1808, the determined surface treatment(s) may be applied to one ormore sheets. In some implementations, these sheets may be a laminate orother material designed to be applied as a sticker, or label to asurface of the device. In some implementations, the sheets may be partof a cover for the device. In some cases, the thermal properties of thesheet may be considered when determining the surface treatments at 1806.

At 1810, the one or more substrates 502 may be applied to one or moredevices that have similar thermal characteristics to the test device. Inthis way, the thermal properties of a device may be altered after thedevice has been sold, such as with an after-market enhancement ofdevices already in use. For example, the one or more substrates 502 maybe incorporated into or provided as an accessory device such as a coverwhich is configured to couple to the device.

Those having ordinary skill in the art will readily recognize thatcertain steps or operations illustrated in the figures above can beeliminated, combined, subdivided, executed in parallel, or taken in analternate order. Moreover, the various elements of the schematicsdescribed above are not to scale or proportional to dimensions ofelements in implementations. Certain proportions of elements may havebeen enlarged or reduced to provide for greater clarity in depictingexample implementations.

Additionally, those having ordinary skill in the art readily recognizethat the techniques described above can be utilized in a variety ofdevices, environments, and situations. Although the present disclosureis written with respect to specific embodiments and implementations,various changes and modifications may be suggested to one skilled in theart and it is intended that the present disclosure encompass suchchanges and modifications that fall within the scope of the appendedclaims.

What is claimed is:
 1. A device comprising: at least one component,wherein heat is generated during operation of the at least onecomponent; a case at least partly enclosing the at least one component;a structure coupled to the case, the structure comprising: a substratecoupled to the case; and at least one feature on a side of the substratethat is proximate to the at least one component, the at least onefeature comprising a thermally conducting material arranged on thesubstrate, wherein the thermally conducting material is more thermallyconductive than the substrate and includes an arrangement of shapesconfigured to conduct the heat across the structure and away from atleast one region on the structure having a temperature above athreshold, wherein the arrangement of shapes includes a regularrepeating pattern.
 2. The device of claim 1, wherein the thermallyconducting material is an anisotropic thermally conducting materialhaving a first thermal conductivity in a first direction and having asecond thermal conductivity in a second direction that is substantiallyperpendicular to the first direction, the first thermal conductivitybeing higher than the second thermal conductivity.
 3. The device ofclaim 1, wherein the thermally conducting material is arranged on thesubstrate in a star-shape having spokes that extend from a point locatedin the at least one region of temperature above the threshold, whereinthe star-shape is radially symmetric around the point.
 4. The device ofclaim 1, further comprising: a thermal conduit extending between the atleast one component and the thermally conducting material, wherein thethermal conduit includes a first width less than a second width of theat least one heat source, and wherein the thermal conduit is configuredto conduct the heat from the at least one component to the thermallyconducting material.
 5. The device of claim 1, wherein the arrangementof shapes includes an arrangement of discrete shapes of the thermallyconducting material.
 6. The device of claim 1, further comprising: anexternal thermal dissipation feature extending from the substrate;wherein the thermally conducting material is arranged between the atleast one region and a location proximate to the external thermaldissipation feature.
 7. A structure comprising: a substrate comprising afirst material having a first thermal conductivity; and a secondmaterial distributed in a pattern on a surface of the substrate, thesecond material having a second thermal conductivity that is differentfrom the first thermal conductivity, wherein the pattern is arranged onthe surface to conduct heat away from at least one hot spot associatedwith at least one heat source, the pattern including an arrangement ofshapes of the second material, at least a portion of the shapes of thearrangement of shapes being at least partially contiguous to facilitateheat conduction; wherein the arrangement of shapes relative to thesubstrate is configured to vary a rate at which the heat is conductedaway from the at least one hot spot based on a distance from the atleast one hot spot.
 8. The structure of claim 7, wherein the secondthermal conductivity is higher than the first thermal conductivity andthe substrate functions as a thermal insulator, wherein the secondmaterial is disposed on a side of the substrate that is proximal to theat least one heat source, wherein all of the second material contactsthe side of the substrate, and wherein the heat is conducted through thesecond material in a direction parallel to the substrate.
 9. Thestructure of claim 7, wherein the second material is distributed on thesurface of the substrate in a shape that is radially symmetric about apoint included in the at least one hot spot.
 10. The structure of claim7, wherein the second material is distributed on the surface of thesubstrate in one or more of a star-shaped pattern, an ellipticalpattern, or a polygonal pattern.
 11. The structure of claim 7, whereinone or more shapes of the arrangement of shapes are asymmetric.
 12. Thestructure of claim 7, wherein the second material is an anisotropicthermally conducting material having the second thermal conductivity ina first direction and a third thermal conductivity in a second directionsubstantially perpendicular to the first direction, the first directionbeing across the surface.
 13. The structure of claim 7, wherein thearrangement of shapes includes a regular repeating pattern.
 14. Thestructure of claim 7, wherein the arrangement of shapes includes anirregular pattern.
 15. The structure of claim 7, further comprising: anexternal thermal dissipation feature extending from the substrate;wherein the second material is distributed on the surface of thesubstrate between the at least one hot spot and a location proximate tothe external thermal dissipation feature.
 16. The structure of claim 7,further comprising: a thermal conduit thermally coupled to the at leastone heat source and the second material for conducting the heat from theat least one heat source to the second material, wherein the thermalconduit includes a first width less than a second width of the at leastone heat source.
 17. A device comprising: at least one component whichin operation generates heat; a structure proximate to at least one hotspot associated with the heat generated by the at least one component,the at least one hot spot having a higher temperature than an averagetemperature of the structure, the structure further comprising: a firstlayer having a first thermal conductivity configured to conduct the heataway from the at least one hot spot; and proximate to the first layer, asecond layer having a second thermal conductivity, wherein the firstthermal conductivity is greater than the second thermal conductivity,wherein the first layer directly contacts and is immediately adjacent tothe second layer, and wherein a distribution of the first layer relativeto the second layer is configured to vary a rate at which the heat isconducted away from the at least one hot spot based on a distance fromthe at least one hot spot.
 18. The device of claim 17, furthercomprising at least one thermal conduit that thermally couples the atleast one component to the first layer, wherein the at least one thermalconduit includes a first width less than a second width of the at leastone component.
 19. The device of claim 17, wherein the first layer is ofa material that is thermally anisotropic, the material having the firstthermal conductivity in a first direction parallel to an interfacebetween the first layer and the second layer, and the material having athird thermal conductivity in a second direction orthogonal to the firstdirection, wherein the first thermal conductivity is higher than thethird thermal conductivity.
 20. The device of claim 17, wherein: thefirst layer is a thermal conductor comprising one or more of a metal, athermally conductive ink, or an allotrope of carbon; and the secondlayer is a thermal insulator comprising one or more of a metal oxide, aplastic, an aerogel, a ceramic, a silicate, or a polymer, wherein all ofthe first layer contacts the second layer.
 21. The device of claim 17,wherein the first layer is arranged in a substantially radiallysymmetric shape about a point within the at least one hot spot, whereinthe shape includes one or more of a star-shaped pattern, an ellipticalpattern, or a polygonal pattern.
 22. The device of claim 17, wherein thefirst layer is arranged in a substantially asymmetric pattern.
 23. Thedevice of claim 17, wherein the first layer includes a materialdistributed in a treatment pattern having an arrangement of discreteshapes.
 24. The device of claim 17, further comprising: an externalthermal dissipation feature extending from the structure; wherein thefirst layer is arranged between the at least one hot spot and a locationproximate to the external thermal dissipation feature for conducting theheat from the at least one hot spot to the external thermal dissipationfeature.
 25. The device of claim 17, wherein the first layer includes amaterial distributed in an arrangement of shapes, the arrangement ofshapes including a regular repeating pattern.
 26. The device of claim17, wherein the first layer is distributed in an arrangement of shapes,at least a portion of shapes of the arrangement of shapes being at leastpartially contiguous to facilitate heat conduction.